From 6c455ac17bcf4beae6c094a1007b976b60b4bb57 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Christian=20K=C3=B6nig?= Date: Wed, 21 Oct 2015 12:58:17 +0200 Subject: [PATCH] dma-buf/fence: add fence_is_later() MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Return true when fence 1 is later than fence 2 without checking if any of them are signaled. Useful for driver specific resource handling based on fences. Signed-off-by: Christian König Reviewed-by: Alex Deucher --- include/linux/fence.h | 22 +++++++++++++++++++--- 1 file changed, 19 insertions(+), 3 deletions(-) diff --git a/include/linux/fence.h b/include/linux/fence.h index a4084d6bb851..bb522011383b 100644 --- a/include/linux/fence.h +++ b/include/linux/fence.h @@ -279,6 +279,22 @@ fence_is_signaled(struct fence *fence) return false; } +/** + * fence_is_later - return if f1 is chronologically later than f2 + * @f1: [in] the first fence from the same context + * @f2: [in] the second fence from the same context + * + * Returns true if f1 is chronologically later than f2. Both fences must be + * from the same context, since a seqno is not re-used across contexts. + */ +static inline bool fence_is_later(struct fence *f1, struct fence *f2) +{ + if (WARN_ON(f1->context != f2->context)) + return false; + + return f1->seqno - f2->seqno < INT_MAX; +} + /** * fence_later - return the chronologically later fence * @f1: [in] the first fence from the same context @@ -298,10 +314,10 @@ static inline struct fence *fence_later(struct fence *f1, struct fence *f2) * set if enable_signaling wasn't called, and enabling that here is * overkill. */ - if (f2->seqno - f1->seqno <= INT_MAX) - return fence_is_signaled(f2) ? NULL : f2; - else + if (fence_is_later(f1, f2)) return fence_is_signaled(f1) ? NULL : f1; + else + return fence_is_signaled(f2) ? NULL : f2; } signed long fence_wait_timeout(struct fence *, bool intr, signed long timeout); -- 2.20.1